TomoHawk

I have a buzzer that I made when fixing the horn wiring & switch. I use it like a test light now.

I'd like to see a DMM that starts with a basic readout with a couple basic functions, like volts and resistance, and the you add on small modules that add more functions that you need, like capacitance, temperature or RPM. Paying several hundred clams for a DMM with lots of special functions doesn't sound right when you just need the basics, but don't want a cheap unit.

I think that's just what a 'smart' DMM will do.

240260280- I was just thinking the same thing: what do you really need in a DMM? That should've the first thing to say in this topic. I think the only fancy thing that's useful on a DMM is a backlight for the LCD display. My barn is dark, unless you have the garage doors open, so the LCD is hard to see, and I usually have a worklight in the car whenever I get in. I think I'll even get a rechargeable LED worklight, so I don't have to drag the damned cord around with me always.

BTW- I was unable to locate the user manual for the multimeter I referenced in the OP, so I looked at the manufacturer's website, and the darned thing doesn't measure resistance! Even with all the other stuff, like bluetooth remote control, data logging, temperature, etc. it wouldn't be of much use to me. An eBay $2 digital thermometer or cheap meter will suffice for temperature and the rest, and I think there's an analog engine tester (RPM dwell, points, etc.) in my dad's toolbox. I even have a cute volt tester made from LEDs and diodes somewhere- it tells you if the voltage is <6volts, over 8, or over 12v. ALSO- Don't bother with the cheap ($3) digital multimeters available at Harbor Freight Tools. They are made withe a cheap Chinese meter chip, and the design is so bad, it tells you your 9V battery has 3487 Ohms! Every other function I tried was wrong as well. It was free at a car show (some unhappy person tossed it in my car for the same reason?) I kept it for a week, thinking a new battery would fit it, but it didn't, so I removed the probes and recycled the rest.

Does your multimeter use some kind of special battery, like the 12V cell you put into a garage door transmitter?

I think they omit a continuity function to simplify the design of the meter. For most of us, a continuity tester would be a "no-brainer." I made my own custom PCB for a continuity tester with a selectible beeper or LED. and probes to test glass fuses. (You do weird things when you get stuck indoors in the winter BTW- I still have old RadioShack Micronta 50K ohm analog meter, but it stays in the house. It's the second I bought of that; the first accidentally blew-up when I was checking 110V and forgot to set the switch. I gave the switch a twist to ACV, and the whole thing was in smoke (when I got to the Ohms range.) It's a good tool to teach the kiddies about volts, ohms, etc. Always set the function switch before you grab the probes...

I've been reading about the usefulness of a multimeter in improving the working of your engine, and I even considered buying one: SainSmart DMT100B 3(5/6) Multimeter Bluetooth Android Datalogger but I thought I'd ask what others use. The devices I read about include functions like frequency, duty-cycle, temperature (thermocouple), peak-hold, data-logging, graphing/bargraph, transistor/diode tester, etc. Some specialized ones for automotive use has RPM, dwell, etc. The one that interested me had a Bluetooth capability to interface with an Android application as a remote-control. So as the title suggests, please share what you use as a multimeter. if you have one, and tell us why you chose or use it. My garage meter is a simple digital meter from RadioShack and has volts, ohms, continuity beeper.

Is it possible to get into a USB jack to "re-wire" the terminals, so you could use it to activate several relays that will power the engine? There are 4 contacts I think, so you could connect those to three relays. What about latching relays? they can toggle things. I have them on the city car to control the turn signals using twp buttons, but I think they open when they lose power. that could be good, if you chain them together like a combination lock. But that's getting to complex, I'd say. I'd still like to know...

The fake lighter you take with you would be better. Hang it around your neck. A desperate thief could start pressing and switching everything (such as the cigar lighter element)out of desperation and get lucky. Any kind of "key" you use to disable the car should be with you when you leave, just like the door lock key does. You should also have several (3 or more) wires coming from your anti-theft device. If it has only two wires, it's kinda obvious to the desperate thief that you should connect them. How about a fake Cat-5 Ethernet connector? You can't shove a paper clip in it to short things, and you could wire the 5 or 7-conductor wire as a kind of "code." A non-powered USB charge port could do it, as it doesn't look out-of-place in a car; it has 4 terminals.

YOu'd have to make the backward rotor. The sensor connector idea sounds interesting, but I'm not sure how you'd do that; it's not easy to work with the sensor wires.

In stead of a switch, a specially made HT wire to create " over-gapped " effect? You just substitute that for the regular HT wire, and it all looks stock. I hate having to open the wiring bundle, but a switch in the 12V line to the coil is starting to look like the desired choice.

Maybe you should label it, Steal my car" and, "not worth stealing." LOL!

The thing that got me to think about this is that if a thief opens your bonnet and sees a switch or something like that interrupting the q12V line to the ignition coil, then he would just jump that and be off with your car. But, if everything "looks" OK, and the engine still won't start, then he might just move on. I would suppose you could splice into the 12V line to the coil somewhere by the brake booster, then it could be disguised. And the more hurdles you can put into the car to prevent someone from driving off with it the better. If you wanted to disable the ECU, will removing one of the green fuse links to that? Doesn't the ECU go into "limp mode" then? BTW- I saw something called an ignition immobilizer on Jaycar.com. It supposedly lets the engine start and a couple seconds later kills the ignition.

One suggestion by "experts" to help protect your car from being stolen is to disconnect the HT wire from the ignition coil, (or remove the rotor, mix up the spark order, etc.) but that seems like an obvious thing for a thief to look for, except for that last one. But what if you had some kind a "dummy wire?" Just disconnecting the HT wire means you will have arcing from the coil, which will harm the coil, and disconnecting only one spark plug will still allow the engine to run, albeit slightly poorly (BTDT ) so if you had a safe way to allow the HT charge to go to ground, the engine will turn over and everything will "look" like it should, but still not start. So what can we do to allow the coil to discharge without going to the spark plugs, and not harming the coil? I'm not referring to cutting the 12V wire to the ignition coil, as that is another thing, and is more involved than just removing the HT wire, so please don't mention that here. BTW- has anyone ever heard of a "G-spot?" It's an electronic doohickey that goes into the starter solenoid wiring and requires to touch it to enable the starter to be activated.

I decided against the Basic Stamp microcontroller because it doesn't have the built in A-D or D-A converters. It's not to difficult to add them, but it does increase the footprint pf the basic board, plud whatever else you want to connect.

The most complex thing I can think of right now is an Air-Fuel ratio analyzer, which might help you to build an ECU. It shouldn't be too difficult once you find a sensor that can sense fuel density in air. There are already oxygen sensors available. IMO, using an "oxygen sensor" in the exhaust stream doesn't qualify as a Ar-Fuel ratio sensor, because it doesn't detect fuel! I can't believe all those people on Youtube, as well as 'tuners' who think an oxygen sensor in the exhaust can tell you the air-to-fuel radio is in the intake airstream.

The Arduino thing looks like it could be a bit of fun. I think I will give serious though to getting some of the stuff, after I pay off some debts from the bodywork, but the available information (Youtube videos and Arduino websites) seems more like hype than help. It basically just tells you how wonderful it is, and you should get one too. But personally, I'm not even sure of which questions to ask, so I will ask those here who have or are using the Arduino stuff, what they would recommend to buy for the beginner. I have experience in making PCBs and C style programming, so you can get technical, if you'd like. I suppose "how much should I expect to spend" would be one question. Will the thing take over my life? Do the projects always get really complicated, or can you do some useful or fun things with only a few parts? Do you run out of capability with a "basic kit" and have to buy the deluxe one right away? Does every project require loads of programming or can you do something with just connecting some parts together, like on a PCB? Can you record data somehow? I would probably prefer to connect it to android tablet when it's not on the workbench (when driving around) One thing that comes to mind would be an exhaust analyzer or a tachometer. Things that you ca do to calibrate the gauges or get the engine running efficiently. thxZ

That is the intent of the test.

You are over-complicating things. You only need the sensor, or in this case, a pressure switch, and no "software" is needed, as you are not measuring absolute values You only need to find high-pressure places that will close the switch. I could probably use the old oil-pressure sender if it was sensitive to low air pressure. The problem here is that the article leaves out information so you can locate a "pressure switch." The one in the photo is used for aviation, and hardly something you might find in a hardware store. I still wouldn't want to get air for the intake manifold from anywhere behind the radiator. You never get enough air too actually cool things.

I was interested in where you can get cool, high pressure air for the intake system, so I thought if I could stick an air-pressure sensor in different places under the hood or even on the outside of the body, I could find a place to get the high-pressure air. Temperature sensors are easy to find, like a thermister. A sensor with an analog output of some kind would be easily monitored: I have a neat LED bar-graph board I made long ago, so I could hook up a sensor to that and watch the lights to see what you can get and where.Thermisters and thermocouples have their own easily-built converters or displays But then, it seems that air pressure sensors are either expensive or just hard to find, so I'm asking you all in case there is a good source. Can you get one from a modern car? A pressure switch: For more information: http://www.autospeed.com/cms/A_113157/article.html

I should probably get the door switches fixed before even considering any kind of an alarm, huh?

The flashing LED is completely self-contained.

I know... You adjust the circuit s0 the LED is ON for 1 second (and off 4 seconds) then hook up to the starter relay, so the starter motor only runs when the LED is on. At least on my car, that takes about 4 seconds to get fuel pressure to start, it would be almost as good as a disabler.

There ought to be a simple way to disable the ECU too. I'm just tired of stringing loose wires behind the gauges.